Polystyrene is a plastic material having many uses and is particularly useful, when in a foam form, as a material for making food containers. It is a significant constituent of municipal solid waste and is particularly prevalent in waste from fast food restaurants, cafeterias and similar food service establishments. Such establishments commonly use trays, containers and cups made of polystyrene foam (PSF).
Fast food restaurant and cafeteria waste in addition to containing large amounts of PSF also commonly comprises a large proportion of paper products (such as bags, cups and napkins), wax-coated paper products, condiment containers, plastic eating utensils and food morsels.
Recycled polystyrene foam can be used to manufacture a wide variety of products such as plant pots, plastic desk organizers, foam construction insulation etc. and is therefore, a valuable product. Further, polystyrene foam, like most plastic, takes a very long time to degrade when placed in landfills. Therefore, it is desirable to recycle polystyrene foam to reduce the amount of such plastic in municipal landfills.
Various apparatus exist for separating recyclable materials from municipal solid waste. One such example is the process disclosed in U.S. Pat. No. 3,848,813 issued to the United States of America for a Continuous Process For Mechanically Separating Materials Contained In Urban Refuse. Most of the prior art in the area of recovering recyclable waste relates to the recovery of glass, metals and paper from municipal solid waste. It has previously been considered unfeasable to mechanically separate PSF waste from municipal solid waste for recycling purposes. The applicants are unaware of any prior art relating to the recovery of PSF from municipal solid waste or fast food restaurant waste.
Therefore, it is an object of the present invention to provide a method and apparatus for recycling polystyrene foam from municipal solid waste and/or fast food restaurant waste.
It is a further object of the present invention to provide a method and apparatus for recovering polystyrene foam and paper pulp from municipal solid waste.
It is another object of a present invention to provide a method and apparatus for recovering polystyrene foam from waste and turning the remaining waste into pelletized refuse derived fuel.
It is yet a further object of the present invention to provide a method and apparatus for recycling waste particles having a specified fluidization velocity.